A tape medium such as a magnetic tape can record a large amount of data at relatively low expense. Since the read and write speed of a tape medium is slower than the read and write speed of a hard disk, a tape medium is often used to preserve data stored in the hard disk for an extended time.
In recent years, the recording density of a tape medium has increased, and thus more data can be recorded. To improve recording density, data recorded at low recording density on a tape medium may be rewritten at high recording density. In Japan Published Unexamined Patent Application No. 2001-067601, a determination is made whether rewriting is possible to realize a desired recording density, and what recording frequency, tape speed, and write current should be set for such rewriting by referring to a table for a combination of the tape type and the recording density. If such rewriting is possible, the recording frequency, tape speed, and write current are set for such rewriting. In Japan Published Unexamined Patent Application No. 2005-092993, highly compressed moving picture data at a relatively higher compression ratio is generated from primarily compressed moving picture data at a given compression ratio and is sequentially recorded in a free area or over the primarily compressed moving picture data of the recording media.
As indicated above, a technique for rewriting data recorded at low recording density on a tape medium at high recording density has conventionally existed. However, errors that may occur during such rewriting are not addressed in the aforementioned applications. Accordingly, in the aforementioned applications, data may be lost if an error occurs when data recorded at low recording density is rewritten at high recording density. In fact, in the context of known art, this issue potentially may arise when converting data format in any scenario.